Cosmetics in one form or another have been around since prehistoric times. Body paint, whether for religious, ritual or ornamental purposes, is an obvious example.
Recorded use of cosmetics dates back 6,000 years in Egypt. Ancient hieroglyphics and portraits reveal extensive accentuation of eyes through the use of make-up. Furthermore, eye make-up preparations including kohl, for lashes and brows, and colored eye shadows have been found in ancient tombs. Dyes were also used on fingers and toes for ornamental purposes.
Powders and sticks of talc, charcoal, and rouge preparations were in use in ancient Greece. The use of the cosmetics spread to the Middle Eastern areas, many of which may have already learned of cosmetics from the Chinese, and into Rome, where extravagant use often required slave-cosmeticians for proper application.
Use of cosmetics waxed and waned, reaching a peak in the Renaissance when both men and women made lavish use of cosmetic preparations.
The twentieth century brought another boom to make-up as the "pace of the times" was increasing due to improved and faster communications and travel. Distant and foreign styles, including cosmetic preparations and applications, spread swiftly and bred more change which in turn spread elsewhere.
The fashion industry became spotlighted by the various medias and advertisements promoted make-up creating an enormous market. The scientific preparation of cosmetics have been fostered and extolled. The market continues to grow as new products and brand names are constantly introduced.
The large market created also insures competition for that market. Product comparison is inevitable and product appearance is one very important basis of comparison. As cosmetics appeal to vanity and the purpose of cosmetics is to enhance personal appearance, the product appearance, along with packaging, etc., is an important factor in consumer acceptance and product success.
Preparations such as nail polish are presented in a manner displaying the product itself, through clear containers or package windows. Preparations such as these contain pigments mixed and suspended in various solvents or make-up bases. Should the incorporated pigments float, settle, striate or separate the product's appearance is adversely affected. A product's shelf-life is dependent upon avoiding these occurrences over time.
Many coatings and methods of treating pigments have been proposed to improve the dispersion and suspension characteristics of nail-polish pigments. Coatings based on lecithin and associated fatty acids such as palmitic, stearic and oleic acids or their salts have been applied to increase pigment dispersion and hydrophobicity. Some examples of an extensive field of research are U.S. Pat. Nos. 4,710,375 (Takasuka et al.), Reissue 31,602 (4,375,989 Makinnen),, 2,068,066 (O'Brien), 1,946,052 (Baldwin) and 1,894,168 (Gardner). Efforts to improve the performance of these dispersion agents include some exotic proposals, for example, use of a phosphorylated fatty acid, U.S. Pat. No. 3,343,974 (Faulkner). Some of the patents in this field relate to paint, and their end products are not suitable for use on humans.
A major drawback arising from the use of fatty acids or their salts is that an adequately uniform coating of the pigments is not achieved: This non-uniformity of the coating can result in agglomeration or floatation of the pigments in subsequent processing, yielding an unacceptable end product.
It has also been proposed to use a silicone coating in a method which calls for the tumbling of the pigment while spraying the pigment with silicone in a 2% solution with a carrier, and then heating the pigment, in the presence of a catalyst, to approximately 70.degree. C. in order to cure the silicone.
This method also suffers from the problems of non-uniformity and complete curing of the silicone does not occur. Untreated silicone can form a layer on top of the liquid make-up. Additionally, uncured silicone can react with moisture and alcohol forming hydrogen gas.
Other drawbacks inherent with the silicone coating process are a reduced gloss of the finished product and reduced hiding power of the pigment. The reduced hiding power can result in requiring up to 25% more pigment in the cosmetic. An increase in pigment further increases the problems associated with non-uniformly coated pigments and uncured silicone on the pigments.
In summary, there has been a longfelt need for a simple system to improve the dispersibilty of pigments to be used in nail polish. In particular, there is a need to provide a system which can be used to pre-treat the pigment before grinding, will coat newly exposed surfaces of the pigment effectively during the grinding process, and can reduce the need for dispersion agents in the end-product nail polish. It is furthermore important that any such pigment treatment system not affect the performance of the pigment, notably its hiding power and color.